Just a Hobby
by RandomFan16
Summary: His family was killed when the Titans attacked the Shiganshina District. He tried joining the Survey Corps, but was rejected. So he decided to do his own training. After three years he gain tremendous power to combat the Titans. Only one problem now, he's so strong that the titans are no match for him. Now he doesn't fight titans for vengeance now he dose it for a hobby.
1. Chapter 1

**Well this is a sorta spurr of a moment kind of thing. I wrote this on my phone so I apologies for any spell or grammar errors.**

 **So Attack on Titan and One Punch Man. I'm going to tell everyone this now, but I'm a bigger OPM fan than I am AOT fan the reason is OPM is so much fun to read while AOT is morally depressing. Tell me why should I get into a serious when most of the people die so grueling painful deaths?**

 **Don't get me wrong the serious is interesting regardless of all the death. The animation is beautiful and I find the titans the most interesting concept along with Titan-Shifters.**

 **The reason I like One Punch Man more is because it's sorta like a parody of all the dark gruesome anime out there. Like Attack on Titan. That's why I reading crossovers for the two. It's one anime interacting with its complete opposite and I really like seeing them interacting with each other.**

 **However now I get into confused territory. On Fanfiction there are no crossovers for One Punch Man and Attack on Titan, buuuuuuuuuut there are crossovers with One Punch Man and Shingeki no Kyojin/** **進撃の巨人** **. Same thing except Attack on Titan is spelled in japanese?**

 **May I ask why?**

 **Anyway my ranting aside this is just something I had to write. I'm not sure if I'll continue this or not.**

 **One Punch Man is owned by One**

 **Attack on Titan is owned by Hajime Isayama**

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He was just an average kid that lived inside the walls. His family lived in the northern most district inside wall rose. Where titan attacks are non existent. Granted it was freezing out but he was used to it.

He lived with his mom, dad, and little brother Mark. They all had fun together and got by just find by farming ice. But he always wanted to start a garden so they wouldn't need to buy supplies from the Military Police those bastards! They always stuck their nose in where it doesn't belong and rob them for more money.

But it wasn't that bad. They rarely come up here because of the lack of titan attacks. But when they do it's the worse.

One day his mom and dad told him and his brother that here going to the Shiganshina District to visit family. He and his brother were excited. Unaware of the horrors that follow.

When they arrived Wall Marie was breached and the titans came and started to eat anyone in there site. That also included his entire family. His mom, dad, aunt, uncle, cousins, and little brother were all killed and eaten. He was the sole survivor saved by members of the survey corps. When they arrived in Wall Rose he was devastated. That was when he swore to kill the same number of titans as members in his family.

His family had four members and his cousins family had six so that would be ten titans in total.

It was only after he completed his quest that he realized he miscounted. He was still alive so he should have just killed nine instead.

He went to live in a orphanage until one year later when he could resisted as a military member. He wasn't very good. He had a stubborn streak before his family was killed and it was made even worse after. He refused to give up even when he felt like he could die from the training.

However he was exempt from training because he couldn't figure out how to work the 3DMG. That alone made him unfit to fight titans. And the members of the corps just told him to go home.

He was angry. And then told them that he would become strong enough to kill titans with one punch. This made the men laugh as he walk away.

He than made his own training program.

One that was superior to the militaries.

One hundred Sit ups

One hundred Push ups

One hundred Squats

And finally a 10k run

Every. Single. Day!

It's been three years since than and now he was 16 and lived on his own with a house in the Trost District. With his very own garden.

Everything was going ok for him. He killed the ten titans a few months back avenging his family in the process.

However there was one thing he didn't realized before taking his vengeance.

Now what?

He had his revenge now what should he do? He was so strong he could end the life of a titan with one well placed punch. However if he didn't aim it right than the titan would regenerate and get back up which annoyed the shit out of him. Why did it had to be the nape of the neck?

Now what should he do. He was at a complete lose. He worked on his garden that was his main goal in life to have the best garden in the world! However it's a slow process. On most days he just watered it and be done for the day. That's it. He needed a hobby.

He was outside Wall Rose one day out of sheer boredom. He needed something to do in his free time but what?

A titan lunged at him, but he spun around delivering a quick punch right into the face obliterating its head in the process. He still wondered what to do in his free time.

Another titan larger than the first attacked him. However he disappeared with pure speed and kicked the titan in the neck sending it flying. What to do?

More and more titans attacked him and he'd made quick work with them without breaking his train of thought. He needed something time consuming.

After looking around the piles of dead titans it finally hit him!

Knitting!

He found his new hobby but then remembered that hat wool and other yarn were so expensive it was out of his budget.. He cursed himself for his idiocy.

Just than deviant type titan came running towards him on all fours. He watched it come at him. He reeled his fist back waiting for the perfect moment before hurling It forward at the titan.

The titan was obliterated as well as everything else behind it. He than looked at the damaged and back at his fist and then the damaged again and smiled.

He would kill titans for a hobby!

He would wake up everyday eat breakfast, water his garden, go out over Wall Rose and kill titans until noon. Come back around noon have lunch, check to see if his garden needs watering and go out past Wall Rose again, and kill titans until dinner than go to sleep.

It got rather repetitive very quickly and he soon found himself so bored from it. The titans were no challenge for him what's so ever. He just needed to punch a titan once to down them for good. It just got so boring.

He even put a few handicaps on himself just to try to make it more challenging. Like only using his legs to kick the titans to death, but it just proved to be more effective.

He than tried to kill titans with out touching them in anyway. But that was kinda pointless since he doesn't actually touch them to begin with. The force from his punches was enough to kill them.

It wasn't long until he grew equally as bored as when he didn't have the hobby. But he kept it up because a boring hobby is better than no hobby right?

One year later and he was still killing titans for a hobby. Deciding to give himself a day off from his hobby he stated within the Trost district and just hang out. He thought it was just going to be a regular day.

That is until he heard an explosion from the wall.


	2. Chapter 2

**Holy crap guys I had no idea this story would take of so quickly. 3 reviews, 4 favs, and 5…. No SIX followers. That is amazing considering this started out as something on my phone.**

 **Well you asked for it so here it is.**

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"What's going on?" He asked to no one in particular as he looked out his window. Everything looked fine that was until he saw a titan walking around the town. He was surprised how did a titan get into the walls?

The titan was about 10 meters high and looking for humans to eat. Deciding it was best to kill it he jump out of his window landing onto the ground before kicking off with his foot launching himself at the titan. He reeled back his fist and punch the titan in the neck. Instantly it was down it fell to the ground while it's neck was obliterated along with the nape.

He landed on the ground and looked as the titan was as it was evaporating releasing massive amounts of steam. He wiped of some sweat on his head. He grew up where the temperature rarely exceeded 30 degrees in the summer months. So he wasn't use to high temperatures. Not to mention the day was already teetering on the hot side AND with the heat of the steam from the fallen titans means that he was very uncomfortable.

He sign at the end of the day the heat was annoying nothing more. He than asked himself how did this titan get in the walls. He leaped up on to the nearest tall building and looked around using his hand to block out the sun to he could see better.

He looked around until he saw a giant hole in the wall and titans were pouring into the city. This was not good sure the titans were no match for him, but the other citizens are in danger. He than looked up higher and his jaw dropped. Standing higher than the wall themselves was a Colossal Titan. It had no skin and was emitting huge amounts of steam.

Any normal person would immediately crap there pants at the sight of this beast, run in the opposite direction, and find a place to hide while they cried out for there mommy. But he wasn't a normal person. He was smiling when he saw the Colossal Titan. This could be the challenge he was waiting for.

Smiling in excitement he crouched down to one knee before releasing the energy. The building he was on cracked due to the seer amount of force he was unleashing before he was launched into the air aimed directly at the wall.

He landed on top of the wall and was smiling as he looked at the Colossal Titan. "Hey!"

The Colossal Titan looked at the man who just suddenly appeared out of nowhere without the 3DMG. "I hope you're made of stronger stuff than your friends were." The Colossal Titan or more specifically the person within the Colossal Titan eyes widen. Did this guy know about the mission? And if he did he kill them? No impossible, but still if this guy knew even remotely about their mission he had to be eliminated.

However before he could eliminate this interloper the two of them heard someone yelling as well as the sound of 3D maneuvering gear being used. They looked to see jumping over the wall spinning.

He rolled his eyes show off.

The boy landed on top of the wall and glared at the Colossal Titan. "Hey there." He said is a very threatening tone. He than starting running towards the Colossal Titan. Ignoring the other person on the wall.

The person inside of the Titan gritted his teeth. He didn't expect Eren to recover that quickly. He closed his eyes and relaxed. This has to be done he told himself. He, as the Colossal Titan, then raised his right arm and swiped it across the top of the wall. However Eren jump up to the avoid the attack as it destroyed the canons.

It was at the moment that Eren realized that the Colossal Titan is intelligent.

"Wow you're slow." The Colossal Titan took a peek at it's right shoulder while making sure to keep an eye on Eren. The person's eyes widen when he saw the man from before on his shoulder.

How'd he get there? He should have been killed during his attack. And even if he did avoid it how did he get on his shoulder. His body was so hot it emitted steam clouds and here this guy was just standing on it like it was ordinary ground.

However Colossal didn't have time to ponder this for long since he than remembered about Eren Yeager. He turned away from the man and looked at the scout. Through the steam he reached out to grab Eren however he used his 3D maneuver gear to grab onto the Colossal Titan's arm and reeled himself in before he could be grabbed.

He attacked the wire from the titans arm and ran up the titans arm. The Colossal Titan lifted its arm up to try to shake Eren off and he succeeded in a way. Eren was off of his arm, but was now going for the his weak spot. The nape of the neck!

Deciding it was time to skedaddle the Colossal Titan emitted a sudden burst of steam from its back just mere moments before Eren could land the killing blow.

Eren was blown back, but recovered and pulled the trigger on his angel to reel himself in an attempt to finish the job. He slashed the steam cloud and discovered that the Colossal Titan had vanished. However Eren wasn't confused at how a titan that big could disappear that quickly for long. The mistress of gravity had taken a hold of Eren and he was plummeting to the ground. He realized this and attacked one of his hooks to the wall to save himself.

However the man who was on the Colossal Titan's shoulder suddenly found himself without any ground to stand on and he fell to the earth outside of the wall.

He picked himself of the ground and dusted himself off. What a bummer he finally found a titan who could potentially be a somewhat difficult challenge for him and then some random kid just flew in and ruin it.

Not to mention his clothes are dirty now.

He sighed and looked to the hole in the wall. That was bad. Everyone in there are at risks of the titans. He than ran back into the city to make sure everyone is safe. He will not let anyone suffer like he did!

However he just needed to run back home for a quick change of clothes first.

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 **Looks like our hero needs to get his priorities straight, but with his speed that should take no time at all.**

 **But still thanks again for supporting this story you guys. See you next time.**


	3. Chapter 3

**Ok now this chapter is going to address something i've been ignoring. Who exactly is "he"? I haven't given him a name or just what exactly he looks like yet. Well it reflects how Saitama got introduced and how we didn't know his name until chapter 6 (or punch 6) in the manga and well to be honest I haven't giving it much thought.**

 **Now since I didn't think that people would like this little story I had to come up with a name for my character. I did and I think it would be an ironic twist.**

 **Now onward! Let us see what is in store for our hero!**

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Mikasa knelt there and detached her hilt from her blade. ' _This world is cruel. But's it's also… it's also beautiful.'_ She thought as the titan walked towards her its footsteps shaking the ground. She looked up. ' _It was a good life.'_

The titan continued a disturbing smile on its face as it looked at it's easy meal. It reached out its giant hand to grab its prey as Mikasa closed her eyes accepting her fate.

However something within her caused her to react. She was going to jump out of the titans reach, but something came swooping in and grabbed her. She was surprised who could have saved her this quickly no 3DMG could move this fast.

She felt her savior stop and let her go. She then got a small twinge of hope that it was Eren.

"Hey you ok." That was until she heard her savior's voice. A voice that was definitely not Erens.

Just some random shoulders.

She open her eyes and was expecting to see a member of the military. Instead she saw a citizen standing in front of her. He wore a dark green long sleeved shirt that was tucked into his brown pants held up by a simple belt. He also wore black shoes. Mikasa raised her head to look at the person's face. His facial features were completely average she wouldn't have been able to spotted him from a crowd. His eyes were green and he had short black messy hair.

She was confused. Where did this random citizen show up and where was the military member that saved her? Did they just left when they saved her? It makes sense there was other problems to address to, but she should have heard the sound of 3D maneuvering gear being used? And also the biggest question of all where in hell did this random citizen come from?

"Hey you ok?" He asked again snapping his fingers to snap her out of it. The ground then began shaking. She turned her head and her eyes widen she she saw the titan from before turning towards them.

Shocked Mikasa got up and stood between the titan and the citizen drawing her blades. "WHAT ARE YOU DOING HERE RUN!" She shouted. There were questions to be answered and she would get them, but the safety of civilians came first.

"Why are you shouting?" He asked as he walked next to her. If completely oblivious to the titan in front of them.

Mikasa looked over at the guy. Was he insane? He was not even scared of the titan and instead wondered why she was shouting?

"I'M SHOUTING AT YOU TO GET AWAY! DON'T YOU NOT REALIZED THE DANGER YOU'RE IN!" She shouted trying to get through to the guy.

"What are you talking about there is no danger?" He said.

Mikasa looked at him. _No danger? He's insane._ As she studied his face she saw that he was looking at the titan in front of them. However instead of fear she saw boredom? Her eyes when wide as he began to WALK TOWARDS THE TITAN!

"WHAT THE HELL ARE YOU DOING." She yelled. How could he possibly take on a titan with no equipment?

He looked over his shoulder back at her. "Would you quit your shouting it's giving me a headache." He said. Mikasa was surprised by his words her winning. A vein appeared on her forehead she was trying to save his ass and he has the nerve to tell to to stop being concern for his safety! She might as well just leave him with the titan.

The man stopped in front of the titan. It smile grew wider as a meal presented itself for it. It reached out for its lunch however the man drew back his fist and launched it forward.

The titan was launched backwards as a giant hole was blown right through it's stomach. It landed on its back and roared in pain.

Mikasa had her eyes wide and her jaw wide open. He just floored a titan with one punch. There was only one question on her mind now.

How?

Mikasa got over her shock and looked at the guy. He was looking at his fist in shock.

He than threw both in hands up and fell to his knees. "NOOOOOOOO." He yelled which confused Mikasa even more. He was upset that he killed a titan?

He than fell to his hands and knees. "Why… does… it… only... take… one... punch!" He said as he slapped his palm against the ground which each word leaving a impressive crack.

Before Mikasa could wonder more about this she looked at the titan and notice it was getting back up! "HEY!" She shouted. The guy heard her and looked up and saw that the titan was getting back up!

"OHHHHhhhh come on!" He said. "Why can't you guys just stay down how come it has to be the nape of the neck that has to get destroyed so you can be considered dead." He than got up and readied himself.

However before he could throw another punch the ground shook again and he and Mikasa looked behind than and saw another titan coming. This one was slim and muscular and it had black hair and pointy ears. It's cheeks were missing giving it a very disturbing smile.

"Oh great." Mikasa said as she readied herself. She had no idea how this guy punched a titan and won, but she highly doubted he could take down two titans.

The muscular titan roared out as he ran over to other titan still getting up the hole in its gut repaired. Completely ignoring Mikasa and the guy. It than began to brutally stop on the other titans head as well as the neck killing it.

' _That titan… he's…. killing the other one'_ Mikasa thought. Surprised by this.

' _That's something you don't see every day.'_ They guy thought also surprised. He than walked back to Mikasa who was still watching the carnage.

"Ain't that a shocker." He said snapping Mikasa out of it. She than redirected her blades at the guy's neck. Him not reacting at all.

"Just who the hell are you?" She asked gritting her teeth. A titan killing another titan may be shocking, but what he did was beyond that.

"I'm just your averaged citizen." He said completely calm.

"Like hell you are! You just punched a hole through a titan!"

"I don't see the problem with it. You're a military member aren't you? You kill titans right"

"Yes, but I use 3D Maneuvering gear. You just flat out punch a titan. How did you do that?"

"I trained. So"

"No amount of training can give you the strength to punch a hole through a titan!"

"Well I did so there is a amount."

"I've had enough of this just who the hell are you."

"I told you.."

"WHAT'S YOUR NAME DAMMIT!"

"Sheesh… my name is Hero O'neil and I kill titans for a hobby."

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 **Well there you have it the name of our hero. Hero O'neil. But what I can hear you typing away. "But RanfomFan16 you magnificent bastard, why dose Hero have hair when Saitama can be mistaken for a light bulb!" Well I'll tell you. My theory is that Saitama wanted to be a hero. No tragic backstory, no vengeance to fuel himself like Geno's, and nothing to prove. He just wanted to be a hero. My theory is that with nothing to fuel the desire to gain strength than the person loses something about themselves. That's why Saitama lost his hair with nothing to fuel his desire he had to lose something.**

 **Now onto Hero he did have something to fuel his desire to kill ten titans. To avenge his family. That's what fueled him to become strong. But after he killed the ten titans and avenged his family his desire for revenge died off and he ended up killing titans not to continue his quest for vengeance, but as a hobby out of sheer boredom.**

 **That's why he still has his hair, his desire for revenge drove him to gain tremendous strength while leaving his hair intact.**

 **Heck we see this in Attack on Titan with Eren himself. He wants to wipe every titan off the face of the earth for vengeance against his mother's death. However he did eventually join the Survey Corps while Hero couldn't work the 3DMG. We see this again when Eren is eaten. He sees the corpses of other soldiers before remembering what fuels him.**

 **Is this theory convoluted. Maybe, but it's what I think is the case and also this is my story. So there.**


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